Conserving whitebark pine in a changing climate
Bioclimatic envelope models (BEM) show a large discrepancy between the current realized and current and future predicted species range for whitebark pine (Pinus albicaulis Engelm.). Large areas in the northwest portion of BC that are projected to become primary refuges for the species under climate change scenarios are hypothetically also potentially habitable under current climate conditions, which begs the question of why whitebark pine doesn’t grow in those areas already. A series of projects have been established to evaluate the biotic and abiotic limiting factors associated with recruitment at the northwest margin of the species range, and the potential for whitebark pine populations to successfully recruit beyond the current species border. Common garden plantings were established within and north of the current northwest species range (50.1° to 59.7° latitude) using seeds from 10 open pollinated families from each of 7 whitebark pine populations (44.3° to 54.9° latitude). Of the 18 common garden sites, six are within the current species range, six are approximately 0.5°, 1.7° and 4.9° north of the current northwest species boundary in locations shown to be habitable under both 1970-2000 normal and 2055 projected climate regimes, and six are parallel to the latter but outside of the modeled range. Results for the first three years of seedling establishment have been published in McLane and Aitken (2012), and results indicate that 1) whitebark seedlings were able to establish and survive in areas predicted to be climatically favourable north of the current species range; 2) the amount of snowpack and snow melt dates are critical to seedling success, with seedling survival low in areas with not enough winter snow pack, or too much. The common gardens have a 20-year permit from the Ministry of Forests and Range, with the expectation that they will be renewed into the indefinite future, and we will continue to monitor these experiments periodically. The project has provided fodder to the current scientific and ethical controversy regarding whether it is acceptable to facilitate the migration of a species threatened by extirpation within (see Aitken and Whitlock 2013) or outside of its current range (McLane and Aitken 2012).